Field of the Invention
The present invention relates to an apparatus for detecting a scene change without any influence from an illumination change or a brightness change of an input image.
Description of the Related Art
In general, an apparatus for detecting a scene change is required to provide functions such as a nonlinear browsing of a video, video index and key fame generation in a personal video recorder and a video database.
FIG. 1 shows one of methods for detecting a scene change, which is using a histogram. In the method shown in FIG. 1, the scene change is detected based upon a bin-to-bin difference method of comparing frequency difference of each bin of the histograms between two input images.
FIG. 1 is a block diagram illustrating a related art method for detecting a scene change. Referring to FIG. 1, two frames being adjacent to each other are input to first and second histogram extracting parts 101 and 102 in order to detect the scene change between the two frames. The histograms of each frame are extracted thereby outputting the histograms to a histogram comparing part 103. At this time, the histogram indicates a gray level distribution of the input image. Each gray level indicating brightness of the image is referred to as a bin, and each bin includes the frequency according to the number of pixels having the corresponding gray level value.
In the histogram comparing part 103 for comparing the two histograms, the histograms are compared in a method of comparing and accumulating the frequency of each bin, as shown in Equation 1.
                    E        =                              ∑                          i              =              0                                      N              -              1                                ⁢                                                                                  h                  1                                ⁡                                  (                  i                  )                                            -                                                h                  2                                ⁡                                  (                  i                  )                                                                                                    equation        ⁢                                  ⁢        1            
At this time, the h1(i) and h2(i) are the respective numbers of pixels of ith numbered bins in the two frames f1 and f2, in which each is the number of pixels having the gray level value of “i” in each image.
The difference E obtained by the histogram comparing part 103 is output to a scene change determining part 104, and the scene change determining part 104 compares the difference E obtained by applying the Equation 1 with a preset threshold value, thereby determining whether the scene change occurs. That is, if the difference E is greater than the preset threshold value, it is determined that the scene change occurs between the two images.
However, the related art apparatus has the following disadvantages.
First, the related art apparatus may have problems when the brightness of the input images is instantaneously changed due to changes of illumination, a camera flash or other optical elements.
Furthermore, the related art apparatus for detecting the scene change has no consideration that histogram distributions of each scene are different from each other when the same scene is photographed in different illumination conditions. Accordingly, even though the scene change does not occur, a false alarm may occur due to an entire illumination change in the related art apparatus for detecting the scene change, thereby making mistakes of determining the scene change.